Java Spring - Writing Excel file and converting to PDF

Question

I'm hoping someone can offer assistance to me. Despite my lack of Java knowledge, I'm currently working on a Java Spring project where we require a service to update an Excel template with certain data and convert it to PDF. The Template RH file can be chosen to be edited using JFileChooser in the code below. A new "Template RH updated" is generated after I'm through writing.

public class GenerateExcel {

public static void fillTable(List<ReportTable> table, Employee employee, String headerMonth) {

    JFileChooser fileChooser = new JFileChooser();
    int click = fileChooser.showOpenDialog(null);
    if(click == JFileChooser.APPROVE_OPTION) {

        try {
            Workbook workbook = new HSSFWorkbook( new FileInputStream(fileChooser.getSelectedFile()));
            Sheet sheet = workbook.getSheetAt(0);

            //HERE WE HAVE THE CODE TO WRITE IN THE EXCEL FILE
            // AFTER WE ARE DONE WRITING IN THE FILE

            FileOutputStream outFile =new FileOutputStream(new File("Template_RH_updated.xls"));
            workbook.write(outFile);
            outFile.close();


        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
}

The first problem is that I wanted to get rid of the JFileChooser. I wanted to get the file from the project itself. I added the template file to the project in:

/myProject/src/main/resources/file/Template_RH.xls

But using:

FileInputStream file = new FileInputStream("/myProject/src/main/resources/file/Template_RH.xls");

is ineffective. What is the proper technique to carry this out? Is it also possible to require the client to download this file while using a browser to call the service?

If anyone knows how to convert this excel sheet to a PDF, please let me know. If there is a library that can't assist me, please let me know.

Answer 1

Since you are using Spring I suggest you load up the file below.

Path to the folder within your project, let's assume your project structure is src/main/java -> contains a package sructure com/aol/app/ src/main/resources -> contains a folder structure similar to above com/aol/app/resources -> where are your files are located, below the path points to the resources folder.

public static final String FILE_CLASSPATH_RESOURCE = "com/aol/app/resources/";

Next use org.springframework.core.io.Resource and org.springframework.core.io.ClassPathResource to load the files, note: this can be any resource.

Resource resource = new ClassPathResource(FILE_CLASSPATH_RESOURCE + fileName);

Once the resource is loaded you can now use the stream to generate the pdf using apache poi.

InputStream is = resource.getInputStream();

Since you mentioned you do not have much exposure to Java, I suggest you follow the below links which show you how to work on excel and pdf.

http://www.baeldung.com/java-microsoft-excel
https://aboullaite.me/spring-boot-excel-csv-and-pdf-view-example/
http://www.baeldung.com/java-pdf-creation